Adhesive products such as labels, stickers, tapes, and similar articles, are normally comprised of a surface sheet or facestock, a layer of adhesive, normally pressure-sensitive, secured to the back face of such surface sheet, and a removable paper backing sheet or release liner secured to the adhesive layer by a low surface-energy bond, such as by means of a silicon coating, for ultimate removal when the label, sticker, or the like, is to be affixed to an article or substrate for end-use purposes. The backing sheet can be difficult to remove because no edge is exposed to facilitate grasping the backing sheet for its removal.
One approach to overcoming the difficulties encountered in removing backing sheets, is to crush-score the backing sheet before it is silicone-released, coated, and applied to the layer of adhesive. Crush-scoring leaves a line in the backing sheet that has been weakened by a compaction of the fibres in the sheet. When a label, sticker or the like is to be affixed, it can be flexed to cause the backing sheet to split or tear along the score line, creating a pair of exposed edges for grasping and peeling off the backing sheet.
The amount of weakening that takes place during crush-scoring, however, must be carefully controlled to prevent splitting or tearing of the backing sheet while it is being processed or prepared for use, and to avoid producing labels, stickers or the like, on which splitting or tearing either occurs prematurely or does not occur upon flexing. Accordingly, a need exists for a means for uniform crush-scoring at a constant and controllable pressure.